'''钟年辉的第三次作业'''
checkStr = input('请输入要判定的字符串:\n')
flag = True
low = 0
high = len(checkStr) - 1
while low < high:
    if checkStr[low] !=checkStr[high]:
      flag = False
      break
    low += 1
    high -= 1
    if flag:
     print('“{}”是回文串。'.format(checkStr))
    else:
     print('“{}”不是回文串。'.format(checkStr))